William "Willie" Francis Tanner is a character from ALF. He is the father figure, and a social worker by trade. Willie is a shortwave radio enthusiast, and it was a result of his shortwave radio signals that ALF followed them and crashed into his home. Willie also avidly collects scale model train sets. He attended Claremont High School, then later graduated from UCLA. When Willie uses his ham Radio to call somebody, he uses the callsign "K726XAA".
He was arrested by the Secret Service after ALF made telephone calls to the President in an attempt to convince the President to deactivate the nuclear weapons program and disassemble America's Nuclear Stockpile, which were misconstrued as the alien trying to threaten the president. Like his wife, he was a flower child during the 1960s.
Willie and ALF have a good, if often strained, relationship. They tend to bicker and snipe at one another, but each will also do their best to come to the others aid in times of strife, though Willie tends to be more strict than ALF would like. Next to Brian, Willie seems to have the strongest bond with ALF out of the cast and the two share as many scenes together, if not more, than do Alf and Brian, Willie's first son. Many of the arguments that the characters often engage in revolve around the cross cultural difference between Earth and Melmac, or sometimes simply come about because of some bizarre behavior Alf is engaging in.
Despite their strained relationship, Willie has referred to ALF as being "amazing" and often marvels at some of the things ALF has revealed about the universe beyond the Earth's solar system. Alf holds Willie in high regard for letting him stay with the Tanners and protecting him from the Alien Task Force and despite their arguments, Alf is usually the first to try to help Willie when things go wrong. He is played by Max Wright.